Floating Wetlands

Environmental degradation disproportionately impacts the poor, adding to issues with basic services and increasing the challenges they already face.

In Chiang Mai, Thailand, household security and environmental quality in Ha Tanwa and other communities living along the Mae Kha canal are threatened by the pollution of the nearby waterway. Faced with government inaction, these communities asked us for help in tackling this issue.

As communities were already active in taking solid waste out of the canal, we worked with them on other water quality interventions. Together we decided to build household wastewater treatment systems to decrease the impact of the communities on the stream, and floating wetlands to improve in-stream water quality.

We co-designed and built rafts planted with vetiver grass to help remove pollution from the canal, contributing to improved environmental quality in a decentralized and visible way. Communities were able to obtain vetiver grass for free through a royal program, and the design involved re-purposing broken bamboo tables from markets in combination with second-hand plastic barrels to create the floating wetlands.

Though the design was simple and went quickly from concept to construct, its location installed in the canal behind houses in Ha Tanwa led to low visibility in the community. In the heavy rain of the summer of 2014, the raft escaped downstream during a flood. It is unknown how it became untied from its anchor, or where it ended up. We can only hope that the vetiver grass survived and is continuing to pull nutrients and contaminants out of downstream waterways.